Rotary drilling machine



Nov. 5', 1935. w. J. MITCHELL ROTARY DRILLlNG .MACHINE Filed May 31, 1953 4 Sheets-Sheet 1 Nov. 5, 1935.- w. J. MITCHELL ROTARY DRILLING MACHINE Filed May 31. 1955 4 Sheets-Sheet 2 3 gmt Mu ff/1 J/y/rc//H L Nov. 5, 1935. w. J. MITCHELL 2,019,761

ROTARY DRILLING MACHINE Filed May 3l, 1935 4 Sheets-Sheet 3 QL m ,MN5 www N wm. wm, l 9v. Q# Y NN w Nm Q mm. Q v N N .3- \m.N\ mw JM lli... A mm.. N /M M ww Ww.

aff/hoffnung4 Nov. 5, 1935. w. J. MITCHELL ROTARY DRILLING MACHINE Filed May 3l, 1935 4 Sheets-'Sheet 4 woamtoc Patented Nov. 5, -1935 UNITED STATES -PATENT- OFFICE ROTARY DRILLING MAcnnvE Application May 31, 1933, Serial N0. 673,728

5 Claims. (Cl. Z55-51) My present invention relates to an improved rotary drilling machine of the high speed, diamond, rock drill type, which, while herein illusmachine, being also adjustable with the machine.

In the exempliedsstructure of the drawings I employ a tubular, sectional, drill rod having a supply of water thereto, and at the end of 'the drill rod a rotary, diamond bit s mounted.

Means are employed for quickly disconnecting the driving connections in order that an additional tube section maybe used on the drill rod, and the 'power unit is mounted directly on the drill rod for high speed in drilling and for compactness and simplicity in the arrangement of the parts of the machine.

The feed mechanism is of the screw operated type and manually controlled, and a spring mechanism is combined with the feed mechanism to impose pressure on the bit at all times, together with means for regulating the pressure.

While the machine is well adapted for various boring or drilling purposes, it is especially useful in drilling holes in hard rock for blasting purposes,` and as distinguished from the hammer type of drills usually employed for blasting, the

drill of my invention reaches aV substantially? familiar.

The invention consists in certain novel combinations and arrangements of parts as will here-` inafter be more fully set forth and claimed. In

the accompanying drawings I have illustrated one complete example of the physical embodiment'oi my invention wherein the parts are combined and arranged according to the best mode I have thus far devised for the practical application oi the principles of my invention, but it will be understood that lvarious Achanges and alterations may be made in the exemplified structure, within the scope of my claims, without departing-from the principlesof my invention. A

Figure 1 is a view in side elevation at therear end oi-the machine embodying my invention. Figure'Z is a .horizontal sectional view, as at 1ine2 2 ofFigure 1.

Figure 3 is an enlarged view showing one of the bearings in section'ior the drill, together with the self centering drive chuck which couples the tubular drive shaft with the tubular drill rod.

Figure 4 is a view showing the driving unit with 5 the thrust bearings of the motor in section.

Figure 5 is a longitudinal, vertical sectional view showing the screw-feed and the tension means combined therewith.

Figure 6 isa transverse sectional view at line 1 0 6-6 of Figure 5, looking toward the front of the machine; and Figure 'I is a similar View at line 1--1 of Figure 5 looking toward .the rear of the machine.

Figure is a vertical sectional view, enlarged, 15 of the front or driving chuck, in locked position, which couples the motor-spindle .or 4tubular drive shaft to the tubular drill rod. n

Figure9 is an inner face view of the head of the chuck showing the pivoted cam-jaws I un- 20 locked and loosely engaging the drill rod.

Figure 10 is a sectionalview of the rear selfcentering chuck.

Figure 11 is a faceview of the rear chuck as seen from the right in Figure 10.

In the preferred form of the inventionas illusy trated in the drawings I employ a rotary diamond bit I illustrated in Figure 1, which is preferably hollow and provided with one or more water holes 2. The bit is coupledat the front 30 end of the front tubular section tk of the tubular drill rod, which as shown is made up of sections. that may vary in length from three feet to twenty feet, and these sections are added at the rear to the drill rod as the boring proceeds. -A water 35 connection 4 in Figure 1 is provided for the drill rod and water is supplied to the bit through the tubular drill rod, from the hose 5 to facilitate the operation of the bit, eliminate dust from the drilling machine, and' to carry off the dbris or 40- cutting of the bit, through the bored hole. For rotating the drill rod and bit I employ a rotary electric motor 6,or other suitable rotary motor may be employed-for this pm'pose that is adapted for directly driving the'drill rod. In the 45 is fashioned with an enlarged portion, within the 55 rotor, that forms end shoulders 9, 9 on the shaft. 'I'he shaft and rotor are mounted to revolve in the motor I and ball bearings I0, I are provided in the motor casing for the drive shaft. In Figure is will be seen that the bearings are located against the spaced annular shoulders 9, 9, of the shaft, and the bearings thus form thrust bearings in combination with the annular shoulders 9, 9, to take up the pressure of the feed mechanism on the drill rod and the drive shaft.

An additional bearing for the drive shaft is provided forward of the motor, which bearing is supported from the drill frame II by a bracket I2, and the bearing head I3 has enclosed therein ball bearings I4. The bearing is of the aligning type and is provided with a retaining end plate I5 bolted to the hollow, circular head I3, and this bearing, as indicated in Figure l is spaced from the motor a suiiicient distance to insure a stable operation of the rotary drive shaft which passes through the bearing, as best seen in Figure 3. 1

The drive shaft is coupled to the enclosed drillv rod by means of a self-centering chuck, located in front of the bearing I3', rigidly mounted on the end of the shaft, and frictionally engaged with the exterior periphery of the drill rod within the shaft. As seen in Figure 8 the chuck or coupling includes a drive head I6, into which the end of the drive shaft is securely threaded, and an enclosing sleeve or shell I'I threaded on the head. Mounted on the inner face of the head within the shell for frictional engagement with the periphery of the drill rod are a number of friction jaws I8 that are caused to grasp the drill rod when the shell is turned, and the latteris provided with a tapered or cone-face ring I9 that rides down the edges of the jaws, forcing the jaws into frictional engagement, with the drill rod, thereby transmitting the rotary motion of the drive shaft to the enclosed drill rod and to the bit I for the drilling or boring operation. 'I'he jaws I3 each have a cam face 2|, and by means of trunnions 20 the jaws are pivoted in sockets in the head and also in complementary sockets of the removable head-plate I6'. A tension spring I8' engages each jaw, and the springs are anchored to the face of the head on pins I1'. 'I'he springs, it will be understood, tend to rock the jaws on their trunnions to released position.'

The cone-ring or wedge-ring `,I9 is limited in .its movement by a split resilient ring I 9 seated in an interior annular groove of the sleeve, and the head plate I 6 is fastened to the head in any suitable manner as by bolts I6a in Figure 9. At the rear endof the motor-spindle or tubular shaft 8 a centering chuck also rigidly joins the spindle with the drill to center the rod. This chuck, as seenvin Figures 10 and 11, includes a tightening sleeve 8 that is threaded on the ex' ternally threaded collar 8a which is mounted on the end of the drive shaft and attachedv thereto by screws or bolts 8b. A split, resilient, tapered clamp ring 8c encircles the drill rodwithin the sleeve 8' and abuts against the end of the drive shaft. By means of an inner cone-face 8d on the sleeve 8' the split ring is centered and clamped on the drill rod to couple the latter with ,the shaft 8.

The drill frame, motor and drive shaft are reciprocable with the drill'rod, and these parts are advanced as the boring or drilling proceeds, the drill frame sliding on a base frame or saddle 22 which is of ample length, and open at its under side. To facilitate the sliding movement of the f is limited by the length of the slot 26 that may drill frame, the base frame is fashionedwith dove-tail grooves 23, and the drill frame is fashioned with complementary dove-tail tongues 24 that co-act in guiding the movement of the drill frame and retain these parts in their proper 5 relative positions.

The upper flat wall of the base-frame is provided with a pair of spaced, central, longitudinally extending slots as 25 designating a wide front slot, and 26 designating a narrow, rear slot, 10 to accommodate the feed mechanism. l

The entire mechanism is usually mounted on the upright column orupon a horizontal arm of the upright column, generally employed in mining operations, and for this purpose I provide a l5 tlunnion 2T that is bolted to the base-frame bymeans ofthe attaching plate 28 located at the under side of the base-frame or saddle 22, and the machine may ,be adjusted at various angles for .drilling or boring. 20

By the use of manually operated feed mecha'- nism the parts supported on. the slidable drill frame II are advanced with the drill frame to the work, and by reverse movement of the feed mechanism these parts are retracted. The feed 25 mechanism operates in connection with a pressure plate 29 that is rigidly attached to the drill frame` by means of the angle bracket 30 which is bolted at 3| to the drill frame. i

The angle bracket projects up through the front 30 slot 25 of the base frame and4 this slot permits the relative movement of the pressure plate within the hollow base frame. On its rear face the pressure plate is fashioned with an annular flange 32 forming a circular cup which is concentric 35 with a central bolt hole or screw hole in the plate, and at its sides theplate is fashioned with a pair of lateral, perforated ears or lugs 33.

The feed screw 34 extends loosely through the center hole of the pressure plate, and at its rear end the screw is journaled in bearings 35 provided in the rear end wall of the base frame, the usual retaining collars 35 being provided to prevent longitudinal movement of the screw as the latter is manually turned through the use of a hand wheel 36 mounted on the end of the screw at the rear of the machine. r

A non-rotating, but travelling nut 31 is mounted on the screw between its bearing and the pressure plate, and this nut has an integral guide lug 33 projecting upwardly from the nut and adapted to reciprocate in the guide slot 26 of the baseframe. As indicated in Figure 6, the guide lug is guided by the side walls of the slot 25, and the nut, integral with the lug is thus prevented from 5i turning on the screw, but is caused to'travel toward and from the pressure plate that is fixed on the drill framejand the range of movement of the traveling nut with relation'to the base frame correspond with the feed of a drill-rod section.

The traveling nut is also fashioned with an annular flange 39 at its front side, forming a cup complementary to and opposed to the cup 32 on thepressure plate, and a tensionA spring 4|! is'05 coiled about the screw and interposed between these two cups for the purposeof at all tim'esl imposing a pressure on the rotary bit I.

At its sides, the traveling nut is fashioned with a pair of lateral, perforated lugs 4I complemen- 70 tary to the lugs 33 of the pressure plate, and two adjustment bolts or tie bolts 42, 42, join these pairs of lugs, one at each side of the screw and spring. The long bolts have heads 43-against the exterior faces of the lugs 4I of the nut, and 'l5 the threaded ends of these bolts which pass loosely through the lugs 33 of the pressure plate are provided with nuts 44 at the exterior sides of these lugs 33. Byturning the nuts on the threaded ends of the bolts the pressure plate, and the parts to which it is attached, are pushed toward the nut, thereby providing an initial compression of the spring 40 between its two cups 32 and 39. During this compression movement, the pressure plate is moved .to the right in Figure 2 along the bolts 42, 42, and the screw 34. Thus an initial tension or resiliency is provided for the drilling machine, before the boring or drilling operation starts, and this tension is exerted through the pressure plate and drill frame, the motor' and the driving shaft, to the drill rod, and-so to the drill bit on the working end of the rod. Thistension is exerted on the drilling rod and bit at all times during the drilling operation, to automatically maintain the bit in operative position. By the use of the hand Wheel, an additional compression is imparted to the spring, as the screw is turned and the nut caused to travel to the left in Figure 2. Thus a resilient pressure is initially imposed on the bit, and thereafter a resilient feed is controlled by the use of the handwheel, the latter being gradually turned as the drilling proceeds to maintain the tension of the spring and the pressure on the pressure plate and drill frame to which it is attached.

After the drill has been advanced or fed the full length of the slot 26 in the base frame, say eighteen inches, or more, the drill is retracted, after the chucks 8' .and I1 have been loosened to uncouple the driving shaft from the drill rod, and permit the tubular drive shaft to slide back on the drill rod. As the hand wheel is turned in direction reverse to the feed motion, the nut 31 is caused to move to the right in the drawings,

and the pressure plate, and the parts to which it is attached, are pulled by the traveling nut through the two tie bolts 42, 42, the screw of course turning, but not moving longitudinally, and the pressure plate slips overthe threaded screw.

If an additional drill rod section is to be added to the drill rod, the water connection 4 is rst removed from the rear end of the drill-rod and then the sectionis added, after which the water connection is again attached at the rear end of the lengthened drill rod. All of the sections of the drill rod are rigidly joined to an adjoining section, and the drill rod isa rigid structure capable of being grasped by the chuck at any point throughout its length.

After the drill frame and its parts have been retracted, the chuck is again coupled to the drill rod, and the drilling operation is resumed.. the feed being controlled by use of the hand wheel.

By means of an indicator or pointer 45 and a scale plate as 46, which is attached rigidly to the drill frame I'I as shown in Figures 1 and '7, the

degree of compression or the tension imposed on the spring 40 may be ascertained by the operator of the drilling machine.

In many instances the expert operator of the drilling machine giving the required close atten' tion to drilling operations, may ascertain by the .feel of the hand wheel and the sound of the trate the relative positions of the nut 31 and the pressure plate 29, and to indicate the normal compression of the spring when these parts are spaced properly; to indicate the sub-normal compression of the spring as when the nut and the pressure plate are too far apart, and the 5 spring is expanded; and to indicate an abnormal compression of the spring when the pressure plate and the nut are too close together.

It will also be apparent that the initial compression of the spring to furnish the tension that 10 holds the bit to its work, may be attained by turning the hand wheel to compress the spring against the resistance of the load of the drill frame and its supported parts.

While I have shown one exemplifying struc- 15 ture for the embodiment of my invention, it will be understood-that changes and alterations are contemplated, and may be made, in Athe illustrated apparatus, within the scope of my claims, without departing from the principles of my in- 20 vention.

Having thus fully described iny invention, what I claim as new and desire to secure by Letters Patent is:

1. In a rotary drilling machine, the combina- 25 tion with a rotary drill rod, of a tubular drive shaft enclosing a portion ofthe drill rod, a drill frame and a supporting bearing on said frame for the shaft, a rotary power unit mounted on the frame'for revolving said shaft, co-acting means 30 on the power unit and shaft to retain the latter against longitudinal movement, and a detachable coupling between the drive shaft and the drill rod.

2. Inra rotary drilling machine. the combina- 35 tion with a rotary drill rod, of an enclosing tubular drive shaft having a pair of spaced exterior shoulders, a drill frame, a power unit mounted on the drill frame, spaced bearings on said unit for said shaft co-acting with said shoul- 4o ders to retain the shaft against longitudinal movement, arevolving element of the power unit fixed on the shaft between said shoulders, and a detachable coupling between the drive shaft and the drill rod. 45

3. In a rotary drilling machine, the combination with a rotary drill rod, of a tubular shaft enclosing a portion of the rod, a drill frame and a supporting bearing on the frame for the shaft,

a motor mounted on the frame and enclosing 50 the shaft, said motor having an element rotatable with the shaft, and a detachable coupling between the tubular drive shaft and the drill rod.

if. In 'a rotary drilling machine, the combina- 55 tion with a rotary drill rod, of a tubular shaft enclosing a4 portion of 'the rod, a detachable coupling between the drive shaft and the drill rod, friction rollers mounted in said coupling for engagement with the rod, means for causing said 00 rollers to grasp the rod, and means for revolving the tubular shaft.

5. In a rotary drilling machine. the combination with a rotary drill rod, a tubular shaft enclosing a portion of the drill rod. a coupling between the drive shaft and the drill rod, friction rollers mounted in said coupling for engagement with the rod, means for causing said rollers to grasp the rod, a drill frame and a supporting bearing on the frame for the shaft, and a rotary power unit mounted on the shaft and frame for revolving the shaft.

' WILLIAM J. MITCHELL.

A.CERTIFICATE 0F CORRECTION.

Patent No. 2,019,761.

November 5, 1935.

l WILLIAM J. MITCHELL.

It is. hereby certified that the name of the assignee in the above numbered patent was erroneously described and specified as "Pneumatic Tool Company" whereas said (Seal) Leslie vFrazer Acting Commissioner of Patents. 

